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The microstructure and optical properties of MgO–TiO2 composite thin films prepared by radio frequency magnetron sputtering were studied. The composite films have an amorphous structure and the growth rate of the composite film increases with increasing Mg content. The refractive index almost linearly decreases with increasing Mg content in the composite films at wavelength larger than 300 nm and can be adjusted in the wide range between the refractive index of TiO2 and that of MgO. The extinction coefficient decreases with Mg content and is nearly zero at visible light region. The optical band gap of the composite films determined from the absorption spectra increases with Mg content, and has a good agreement with that obtained from spectroscopic ellipsometry simulation. A broad photoluminescence band in the visible region was observed in the composite films with high Mg content and was considered resulted from the oxygen vacancies. [ABSTRACT FROM AUTHOR]

Nanocrystalline compound thin films of ZnO-TiO2 with different Zn/Ti atomic ratios were prepared by radio frequency magnetron reactive sputtering. The optical constants and the optical band gap were investigated using spectroscopic ellipsometry and the optical absorption spectrum. It was found that the cubic ZnTiO3 phase can be obtained with the atomic ratio of Zn to Ti of about 1:1, and transforms to rhombohedral ZnTiO3 phase and a phase mixture of rhombohedral ZnTiO3 and ZnO with increasing Zn content. The refractive index decreases with the increase of Zn content, and the extinction coefficient in the visible range is near zero. The optical band gap was derived from the modeling of ellipsometry data and extinction coefficient spectra, and compared with that obtained from optical absorption spectrum, and it was found that the optical band gaps obtained by these three methods are consistent with each other. [ABSTRACT FROM AUTHOR]

Distributed feedback lasing characteristics of oxazine dye in zirconia waveguides and in solutions were investigated. Oxazine-dye-doped waveguides were characterized by ellipsometry. Intensity modulation and polarization modulation were used to generate laser action. Tunable narrow line width laser action was achieved for the first, second, third and fourth Bragg orders. It was observed that the threshold pump energy decreased with the decrease of the Bragg order. The degree of polarization of the laser output also changed from 0.8 at the third Bragg order to 0.1 at the first Bragg order. Wide-band tuning of the distributed feedback laser output from 700 nm to 870 nm was achieved for the first-order action during intensity modulation. [ABSTRACT FROM AUTHOR]

The optical properties of δ-Bi2O3 thin films were investigated using spectroscopic ellipsometry and optical absorption spectrum. δ-Bi2O3 thin films were grown on Si and quartz substrates under different oxygen flow ratios (OFR) by radio frequency reactive magnetron sputtering. The Tauc-Lorentz dispersion method was adopted to model the optical dispersion functions of the thin films. The optical bandgap was obtained by three different methods. It was found that refractive index and extinction coefficient decrease, and the optical bandgap has a slight blue shift with increasing the OFR. Factors influencing the optical constants and optical bandgap are discussed. [ABSTRACT FROM AUTHOR]